Frequencies for first 10,000 rows of contsub4 variable in nhamcsed2008 dataset :

       for rx4, controlled |
     substance status code |      Freq.     Percent        Cum.
---------------------------+-----------------------------------
               schedule ii |        152        1.52        1.52
              schedule iii |        114        1.14        2.66
               schedule iv |         50        0.50        3.16
                schedule v |          5        0.05        3.21
                no control |      1,307       13.07       16.28
              undetermined |         28        0.28       16.56
        multiple schedules |          6        0.06       16.62
                         . |      8,338       83.38      100.00
---------------------------+-----------------------------------
                     Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016